25 Best EJB Interview Questions and Answers

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EJB Interview Questions and Answers List 1. Are enterprise beans allowed to use Thread.sleep()? 2. Is it possible to write two EJB’s that share the same Remote and Home interfaces, and have different bean classes? 3. Is it possible to specify multiple JNDI names when deploying an EJB? 4. Is there any way to force an Entity Bean to store itself to the db? 5. I am developing a BMP Entity bean. I have noticed that whenever the create method is invoked, the ejbLoad() and the ejbStore() methods are also invoked. I feel that once my database insert is done, having to do a select and update SQL queries is major overhead. is this behavior typical of all EJB containers? Is there any way to suppress these invocations? 6. Can an EJB send asynchronous notifications to its clients? 7. How can I access EJB from ASP? 8. Is there a guarantee of uniqueness for entity beans? 9. How do the six transaction attributes map to isolation levels like “dirty read”? Will an attribute like “Required” lock out other readers until I’m finished updating? 10. I have created a remote reference to an EJB in FirstServlet. Can I put the reference in a servlet session and use that in SecondServlet? 11. Can the primary key in the entity bean be a Java primitive type such as int? 12. What’s new in the EJB 2.0 specification? 13. How many types of protocol implementations does RMI have? 14. What is the need of Remote and Home interfaces. Why can’t there be one? 15. What is the difference between Java Beans and EJB? 16. Question With regard to Entity Beans, what happens if both my EJB Server and Database crash, what will happen to unsaved changes? 17. Question Can you control when passivation occurs? 18. Does RMI-IIOP support dynamic downloading of classes? 19. Does EJB 1.1 support mandate the support for RMI-IIOP ? What is the meaning of “the client API must support the Java RMI-IIOP programming model for portability, but the underlying protocol can be anything” ? 20. The EJB specification says that we cannot use Bean Managed Transaction in Entity Beans. Why? 21. Can I invoke Runtime.gc() in an EJB? 22. What is clustering? What are the different algorithms used for clustering?

23. What is the advantage of using Entity bean for database operations, over directly using JDBC API to do database operations? When would I use one over the other? 24. What is the role of serialization in EJB? 25. What is EJB QL?